Ultrasound imaging systems can be used to visualize subcutaneous body structures, such as organs, muscles, embryos, joints, and vessels. Typically, ultrasound imaging systems include a processing station (e.g., a computer) operably coupled to an ultrasound scanner. The ultrasound scanner includes an array of piezoelectric transducers that are linked independently to the processing station by individual communication lines housed within a cable. During an ultrasound scan, each transducer in the array both transmits acoustic waves into a body toward a target site and detects echoes from the acoustic waves as they reflect off of internal body structures. The received echo data is then transmitted to the processing station, where images of the scanned internal structures can be formed, manipulated, and displayed.
Transmitting nonlinear acoustic waves can enhance the resolution of ultrasound imaging because harmonic frequencies have higher signal to noise and higher contrast to noise than the fundamental frequency. Additionally, the properties of the internal structures can impact the harmonic frequencies such that the harmonic scatter in the received echo may be used to derive information related to the internal structures. Conventional ultrasound scanners, however, lack the sensitivity to detect meaningful amounts of harmonic scatter.